v0.2.0

This release:

• Fixes chunked file reads (buffer overflow + missing P suffix in CAS paths)
• Fixes FUSE FileAttr construction (flags, nlink, rdev)
• Fixes statistics counters (self_* instead of subtree_*)
• Adds RSA-PKCS1v15-SHA1 signature verification on repository manifests
• Adds 69 integration tests covering repository, catalog, history, filesystem, and fetcher operations
• Adds 91%+ code coverage with Codecov integration
• Adds Makefile with common development targets
• Adds cargo-nextest support in CI
• Uses serial_test to prevent concurrent test interference on shared CERN servers
• Rewrites README with library usage examples and quick start guide